There is a wide range of image file formats that can be used on websites, In this article we explore the different formats and their pros and cons of use.
The choice of image normally depends on factors like quality, file size, and the type of image you're using. Here’s a breakdown of the most commonly used formats and their pros and cons:
1. JPEG (.jpg or .jpeg)
The JPG was first invented in 1992, the acronym JPEG is derived from the full name ‘Joint Photographic Experts Group’.JPEG files are typically smaller than other image file formats, due to the levels of compression used.
In general JPG images are best used for photographs and images with lots of colours or gradients (e.g., photos, illustrations).
Pros of using JPG images:
- Compression: JPEG images are highly compressed, meaning they have smaller file sizes, which is great for website performance.
- Good balance between quality and file size: It’s a widely used format because it strikes a good balance between quality and file size.
- JPEG images can be easily converted into other file formats with little or now quality loss.
Cons of using JPG images:
- Lossy compression: When you compress a JPEG, some image quality is lost (though you can adjust the compression level to find a good balance).
- No transparency: JPEGs cannot handle transparency like PNG or WebP.
- JPEG are known to be difficult to edit, due to the compression used.
2. PNG (.png)
Portable Network Graphics, PNG for short, are one of the most popular image formats used on websites, this is because they offer background transparency, allowing images to be ‘cut out’ from their background, this does however increase the file size due to less compression.
PNG images are best for Graphics, logos, illustrations, icons, or images with transparency.
Pros of using PNG images:
- Lossless compression: PNG images retain their original quality, so you don’t lose detail.
- Format is suitable for storage of intermediate versions of the image. When you re-save image, quality is not lost;
- Transparency: PNG supports transparent backgrounds, which is ideal for logos and icons.
- High-quality images: PNG is excellent for images with sharp lines or text.
Cons of using PNG images:
- Larger file sizes: PNG files can be much larger than JPEGs, especially for complex images.
- Slower load times: Due to their larger file size, PNG images can slow down page load times if not optimized.
- PNG files do not support animation.
3. WebP (.webp)
WebP stands for Web Picture and is a modern image file format developed by Google. WebP images are designed to provide superior lossless and lossy compression for images on the web.
WebpP images are best for: Both photographs and graphics. It's a newer format that’s becoming more popular for web use.
WebP images were designed to become a replacement for JPEG, PNG, and GIF file format
Pros of using WebP images:
- Superior compression: WebP offers both lossy and lossless compression. It often provides much smaller file sizes compared to JPEG and PNG without sacrificing quality.
- Supports transparency: WebP supports transparency like PNG but with smaller file sizes.
- Good quality: WebP images can deliver similar or better visual quality than JPEG, often with smaller file sizes.
- Faster loading times—Due to the smaller file sizes, pages with WebP images load faster.
Cons of using WebP images:
- Browser support: While most modern browsers support WebP, older browsers (especially Internet Explorer) don’t, so you might need a fallback image format (e.g., JPEG or PNG).
- Editing: WebP images may not be as easily editable as JPEG or PNG.
- Quality is still reduced - Not so much a disadvantage of WebP as a disadvantage to all lossy compression.
4. SVG (.svg)
SVG stands for Scalable Vector Graphics. It's a vector image format that uses mathematical formulas to define images, allowing them to be scaled to any size without losing quality.
SVG images are best used for Vector images like logos, icons, and illustrations that need to scale infinitely without losing quality.
Pros of using SVG images:
- Scalability: SVGs are vector-based, meaning they don’t lose quality when resized, making them ideal for responsive web design.
- Small file sizes: SVGs can have very small file sizes compared to raster formats like PNG and JPEG.
- Interactivity: SVGs can be manipulated via CSS and JavaScript, offering the ability for animations and interactive effects.
Cons of using SVG images:
- Limited to vector graphics: Not suitable for complex images like photographs.
- Security concerns: SVG files can contain malicious code, so they need to be sanitized before use on websites.
5. GIF (.gif)
GIF is an acronym for Graphics Interchange Format, a file format that supports both static and animated images. GIFs rose to popularity as a way to react on social media without words. Facebook and Twitter both support animated GIFs.
GIFs are best used for simple animations or small, low-colour images.
Pros of using GIF images:
- Supports animation: GIFs are the go-to format for simple animations on the web.
- Widely supported: GIFs are supported by nearly all browsers and platforms.
Cons of using GIF images:
- Limited colour range: GIFs only support 256 colours, which makes them less suitable for complex images or photographs.
- Large file sizes: Animated GIFs can get quite large, which can slow down your website.
6. AVIF (.avif)
AVIF (AV1 Image File Format) is a modern, open-source image format designed for high compression efficiency and quality. It leverages the AV1 video codec to achieve smaller file sizes and superior image quality compared to traditional formats like JPEG and WebP.
AVIF images are best used for high-quality images with low file sizes (emerging format).
Pros of using SVG images:
- Superior compression: AVIF offers much better compression than JPEG, PNG, and WebP, meaning smaller file sizes for high-quality images.
- Lossless and lossy compression: AVIF supports both types of compression.
- High-quality visuals: It offers excellent quality, including HDR support.
Cons of using SVG images:
- Limited browser support: Like WebP, AVIF is still gaining support across browsers, though it’s gaining traction (currently supported by Chrome, Firefox, and Opera, but not by Safari yet).
- Encoding time: Encoding AVIF images can take longer compared to other formats.
Best Practices for Web Image Formats
- Use WebP: If possible, WebP is generally the best option for modern web design due to its superior compression and quality.
- Fallbacks: Since WebP doesn’t have universal browser support, you may want to use a fallback format like JPEG or PNG for unsupported browsers.
- JPEG for photos: If you’re dealing with photographs, JPEG (or WebP if supported) is usually the way to go.
- PNG for transparency: If you need transparency (e.g., for logos or icons), go with PNG or WebP.
- SVG for logos and icons: For simple graphics and logos, SVG is ideal because of its scalability and small file sizes.
- GIF for simple animations: If you're using animations, GIFs can be useful, though WebP can be a better alternative in terms of file size and quality.
Conclusion on image formats for websites:
For most websites, WebP is emerging as the best format overall due to its smaller file sizes and good quality, especially for images like photos and graphics. However, if you need universal compatibility, JPEG for photos and PNG for images with transparency are still solid choices.
Make sure to optimize your images for the web (using tools like TinyPNG, ImageOptim, or similar) to reduce their file size and improve page load times!
